Cam switch



V. R. DESPARD SWITCH Feb. 16, 1954 Filed July 23, 195i 2 Sheets-Sheet 1INVENTOR.

v; c'ro DESPBRD BY 9 m AT TORNEZYS Patented Feb. 16, 1954 CAM SWITCHVictor B. Despard, Syracuse, N. Y., assignor to Pass & Seymour, Inc.,

ration of New York Syracuse, N. Y., a corpo- Application July 23, 1951,Serial No. 238,054

6 Claims.

This invention relates to switches and more particularly to wallswitches of the lever operated alternating current type.

It is a general object of the present invention to provide a novel andimproved switch of the lever actuated alternating current type wherein acontact mounted intermediate the ends of a cantilever leaf spring iscammed toward and from a stationary contac More particularly it is anobject of the present invention to provide in a switch of the typedescribed a novel operating mechanism for a contact carrying leaf springcomprising an operating lever mounted to oscillate in a planesubstantially parallel to that of the spring leaf and fitted with a facecam to engage the free end of the spring and flex it in contact closingdirection.

An important object of the present invention resides in the provision ofmeans on the cam carrying operating lever for applying a positiverelease pressure on the spring for disengaging the contacts.

Another important object of the invention resides in the side-by-sideassembly of two sets of operating contacts arranged for alternateopening and closing by cams on the single operating lever.

A further important object of the invention comprises quieting means forlimiting and cushioning the movements of the operating lever 4 whichacts under the direction of an over-center spring.

An important feature of the invention resides in the unique assembly ofthe fixed and movable parts of the switch housing.

Other and further objects and features of the invention will be moreapparent to those skilled in the art upon a consideration of theaccompanying drawings and following specification wherein is disclosed asingle exemplary embodiment, with the understanding that such changesand modifications may be made therein as fall within the scope of theappended claims without departing from the spirit of the invention.

In said drawings:

Fig. 1 is a longitudinal central section, through a switch constructedin accordance with the present invention, taken on broken line l-l ofFig. 2;

Fig. 2 is a top plan view thereof with the cover and operating leverremoved and showing the contact assembly and construction;

Fig. 3 is a transverse section taken on broken line 3-3 of Fig. 1;

Fig. 4 is a longitudinal section through the construction in theenclosing meeting plane of the of Fig. 2;

Fig. 5 is a fragmentary section taken on line 5-5 of Fig. 3 andillustrating the operating lever buifer;

Fig. 6 is a fragmentary section taken on line 6-6 of Fig. 1 showing themounting of the terminal separating insulator; and

Fig. '7 is a side elevation of the operating lever illustrating thecontact-spring actuating cams.

The switch of the present invention is preferably fully encased for usein switch and wall boxes and the like, and for this purpose a onepiecemolded insulation housing includes the enclosed bottom ll, slotted endwalls I: and I3, solid side walls l4 and I5 and an open top. A cover Itserves to close the opening in the housing and is positioned and securedby a metal collar l7 forming no part of the present invention.

The cover I 6 is provided with an elongated opening I8 for the passageof handle I9 from operating lever l9, which handle extends outside thehousing for manual manipulation. This lever is preferably moldedintegrally from suitable insulating material and includes laterallyprojecting trunnions received in complementary shaped half notches 2!(see Figs. 2 and 3) in the side walls of the housing and cooperatinghalf notches in the cover whereby it is journalled for oscillation inthe manner of the usual toggle switch lever. A depending arm 22 on thelever is fitted with a semi-spherical lower end 23 adapted to bear on ahelical compression spring 24 whose opposite end rests on thesemi-spherical end of a stud 25 projecting up from the bottom of thehousing. Both this stud and the arm depending from the lever havefulcrum wings 26 thereon to support the spring. The arrangement justdescribed provides a lever with an over-center spring, which insures itmoving to either of two extreme positions when turned beyond the center.

To provide limit stops for the operating lever a recess 28 in theextended neck portion of the cover receives a block of suitableresilient material 29 having a flat under face which cooperates with theclipped corners 30 of a lateral protuberance 3i on the operating leveradjacent one of the trunnions 20. The stopping engagement between acorner 30 and the cushion member serves to silence the operation andlimit the movement of the lever in either direction.

The face of the lever opposite that fitted with the cushion engagingportion is provided with a pair of cams 33 spaced on either side of thecorresponding trunnion, as best seen in Fig. '7.

contacts taken on line 4-4 These are shown as rectangular in elevationand each includes a relatively square flat dwell portion 34 and aconcave surface 35 which substantially merges with the side face of thelever unit. The trunnion on the same side of the lever as the cams isprovided with a depending rectangular arm 3! having a flat radial innerface, seen best in Figs. 3 and 4, and well spaced outward from the cams.

The switch is of the A. C. type, that is, it is intended to open andclose alternating current circuits only. Here, after an initial minuteopening between relatively large contacts, the arc is quenched ascurrent passes through zero, and does not restrilre. This type of switchis preferably equipped with a pair of silver contacts for each circuitto be opened and they are of substantial diameter and preferably convexon the meeting faces to insure good engagement in the event ofinaccurate confrontment. Two pairs or" such contacts is arranged foralternating actuation by the cams, in the switch shown, in order toprovide what is commonly termed a three-way or lazy mans switch but moreproperly termed a single pole double throw switch. of each pair isstationary, while the other, shown at Al, is movable and carried at suchan intermediate position between the ends of a cantilever leaf spring 43that it is situated at a nodal point resulting from flexure of thespring. This provides for minimum vibration and chattering on closingthe circuit.

These leaf springs are preferably formed inte'gral with and bent up fromthe sides of a con necting elemental which is received in a shallowrecess in the bottom wall and is riveted at A to a heavy transversestrap is which extends the full length of the bottom wall and has formedintegral with one end thereof an upturned terminal plate Mlwhich extendslaterally into the vertical slots 49 in the corners of the housing, asseen'in Fig. The opposite end of the strap is widened to provide a pairof prongs received in similar slots in the opposite corners of thehousing. A terminal screw 50 is threaded into the terminal plate, afterassembly, and its head is available in slot 52 in end wall It of thehousing One edge of the strap at is offset to clear the stud 25 and thecontact carrying springs extend upwardly from the opposite edge, as seenin Fig. 2, into proximity to the paths of the cams The extreme upper endof each spring is sharply bent toward the cam and then reversed, as seenat 5 3 in Fig. 3, to provide a transverse ridge bearing on the surfaceof the corresponding cam resulting from the initial set and shape of thespring. This ridge bears on the cam from the open circuit position shownat the right in Fig. 4 to the closed circuit position shown at the lefttherein. In the open circuit position, the ridge on the free end of thespring is at the lowermost portion of the concave section of the cam andduring movement of the lever the cam moves beneath the ridge until itfinally rests on the dwell section 33 and holds the circuit closed withconsiderable ilexure of the spring to insure against chatter.

Each contact carried by one of the springs is adapted to cooperate withone of the stationary contacts 56. These are supported from oppositeends of the housing by similar but reversely formed arms Gil which arebent up at right angles from terminal plates iii, and whose ends extendinto the corner slots 9 for support against movement. Where each arm 69springs from its terminal plate 5! suitable slits are provided so thatQne contact the arm is free from the side wall of the housing. Thecontact til is shown as riveted to the end of the arm, which is suitablywidened for the purpose. The contacts of a pair normally confront eachother, as seen in Fig. 3, with the spring tending to move them towardopen circuit position, but only one circuit can be opened at a timebecause at the manner of cooperation of the cams with the ends of thesprings.

To insure positive openings of the contacts in the event that thereshould be some tendency to stick from arcing or heating, the positivekick-off lever 31, depending from the trunnion as previously described,is arranged to selectively cooperate with lateral tongues near the upperends of the springs. These tongues project toward each other, as shown,and their ends are formed to provide ridges in the same manner as theends which engage the cams. The ridges however are vertical and face tothe opposite sides of the springs. Thus when a cam moves from beneaththe end of a spring the lever 31 moves over the tongue 65 thereof, asseen in the right of Fig. 4, to positively retract the upper end of thecontact carrying spring and thus separate the contacts under allconditions.

The end of the spring carrying strap 45 re-' mote from its terminalplate is positioned and held down by a sheet of insulation 63 slidvertically into grooves til as seen in Figs. 1 and l. The terminal plate6% for one of the stationary contact arms rests on the upper edge ofthis sheet and the whole is clamped by the housing cover It as shown. Atthe opposite end of the housing the stacked terminal plates 4% and SIare similarly clamped. They are insulated from each other by a sheet ofinsulation it, Figs. 1 and 6., horizontally positioned and notched at 'Hto engage the walls of slit 52 in the end of the housing. The outwardextension of sheet it serves as a barrier between terminal plates andscrews.

It will be clear that a single pole switch will be formed if one set ofcontacts is omitted and that double pole and four-way switches only require the duplication of the two sets of contacts which can be placed onthe opposite side of the operating lever and appropriately connected ina manner well understood.

The above-described switch is simple in construction, has few parts, isquiet and effective'in operation and capable of handling substantialcurrents with a minimum of destructive arcing.

I claim:

1. In aswitch' of the type described, in combination, a stationarycontact, a movable contact, a leaf spring cantilevered at one end andhaving a free end, said movable contact being mounted intermediate theends of and urged to open circuit position by saidspring, an operatinglever mounted for limited oscillation in a plane adjacent andsubstantially parallel to that of the spring, a face cam on said leverpositioned to engage one face of the free end of the spring and flex itinto contact engaging position when the lever is at one end of itsstroke, and means on said lever to engage the opposite face of said freeend as the lever approaches the other end of its stroke to flex thespring toward contact separating position.

2. In a switch of the type described, in combination, a pair oflaterally spaced cantilever leaf spring each having a fixed and a freeend, a contact intermediate the ends of and on the same face of eachspring, a stationary contact norm-ally spaced from each fixed contact,an operating lever journalled for limited oscillation in a planesubstantially parallel to that of said springs, cam surfaces on saidlever for cooperation with the free end of each spring, said surfacesbeing so shaped and positioned that one engages the baolr face of andcloses one set of fixed and movable contacts while the other releasesthe back face of the second set and vice-versa, and a separateoppositely facing surface movable with said lever to engage the frontface of the spring whose contacts are being released to insure contactopenmg.

3. The switch of claim 2 in which said operating lever is equipped withan over-center spring to hold it at either limit of movement, andresilient buffer means positioned to determine said limits.

4. The switch of claim 2 in which the separate surface on said lever isflat and each spring is provided with a laterally extending tilted tabfor engagement thereby, whereby the contacts are relatively rocked forsaid release actuation.

5. An A. C. switch having in combination a boxlike open top housinghaving closed side walls and bottom and slotted end walls, a metal strapextending along said bottom and having a terminal exposed through one ofsaid end walls, a pair of flat cantilever springs symmetricallyextending from the strap toward the top of said housing, a cover forsaid housing, a lever having a handle portion extending through saidcover and trunnions journalled between the centers of the upper edges ofthe side walls and said cover, an open coil spring, an inward extensionon said lever compressing the spring against said bottom wall to providean over-the-center action for the lever, a contact on each springintermediate its ends and facing the nearer side wall, a stationarycontact facing each spring mounted contact, a rigid strap mounting eachstationary contact, supported by the housing and having a terminalexposed through one of said end walls, said lever having a radial faceconfronting said last mentioned side wall, two cam surfaces on said facepositioned to alternatively flex said springs to engage thecorresponding contacts, said springs normally biasing the contacts open,and means carried by one of said trunnions to engage the rear face ofthe spring released by a cam surface to positively separate itscontacts.

6. In a switch of the single pole, double throw type, in combination, ahousing, an operating lever assembly trunnioned for limited oscillationtherein, an over-center spring adjacent one side of and associated withsaid lever-assembly to hold it in definite off and on positions, a pairof face cams on the other side of said assembly oppositely disposedabout the axis of trunnioning, a pair of stationary contacts supportedby said housing, mating movable contacts one for each stationarycontact, a leaf spring cantilevered from the housing for each movablecontact and supporting the same intermediate the spring ends and urgedtoward open circuit position, each spring being in a plane substantiallyparallel to the plane of movement of said cams and with its free endpositioned to be engaged by one of said cams at one of its limits ofmovement to fiex the spring into contact engaging position, and meansconnecting the contacts of one pair together and forming a terminal forthe same.

VICTOR R. DESPARD.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,023,491 Anderson Apr. 16, 1912 1,200,847 Kaisling Oct. 10,1916 2,014,474 Hopkins Sept. 17, 1935 2,203,224 Kimball June 4, 19402,253,968 Cook Aug. 26, 1941 2,293,318 Thirlwell Aug. 18, 1942 2,314,465Shaw Mar. 23, 1943

